There are many methods used at present to apply solder to wafers, ceramics, laminate and flex circuit boards, and other substrates. Among these, high-precision solder droplet printing technology, which is noncontact, data driven, flexible and environmentally friendly, is a key enabling technology. This technology selectively deposits solder droplets only where required, and therefore needs no mask or secondary resist removal, uses materials more efficiently and creates less waste than other methods. Currently, continuous droplet formation from capillary streams is mainly achieved by application of the well-known Rayleigh instability in which a sinusoidal disturbance is applied to the stream, resulting in evenly spaced and sized droplets. However, changing droplet configurations for various products or varying the size or depth of solder joints is difficult. Amplitude modulated disturbance is employed in this work to generate arbitrary solder stream configurations. The final configuration is mainly determined by several parameters: (1) the degree of modulation of the waveform; (2) the phase difference between the carrier and modulation signals; (3) the charging voltage; and (4) the frequency ratio between the carrier signal and the modulation signal. Many different patterns can be achieved with the proper combination of frequency ratio, phase difference, degree of modulation, and charging voltage. A simulation code was developed to simulate the merging process and determine the parameters needed to achieve certain droplet configurations

Meeting Name

International Symposium on Advanced Packaging Materials: Processes, Properties and Interfaces, 2001


Mechanical and Aerospace Engineering

Keywords and Phrases

Rayleigh Instability; Amplitude Modulated Disturbance; Amplitude Modulated Droplet Formation; Amplitude Modulation; Arbitrary Solder Stream Configurations; Assembling; Capillarity; Capillary Streams; Carrier Signal; Carrier Signal/Modulation Signal Frequency Ratio; Carrier Signal/Modulation Signal Phase Difference; Ceramics Substrates; Charging Voltage; Continuous Droplet Formation; Data Driven Process; Degree of Modulation; Droplet Configurations; Drops; Electronic Engineering Computing; Environmentally Friendly Process; Evenly Spaced/Sized Droplets; Flex Circuit Boards; Flexible Process; Flow Instability; Laminate Circuit Boards; Materials Usage Efficiency; Merging Process; Modulation Signal; Noncontact Process; Packaging; Process Waste; Secondary Resist Removal; Selective Deposition; Simulation Code; Sinusoidal Disturbance; Solder Application; Solder Droplet Printing; Solder Droplet Printing Technology; Solder Droplets; Solder Joint Depth; Solder Joint Size; Soldering; Wafers; Waveform Modulation

Document Type

Article - Conference proceedings

Document Version

Final Version

File Type





© 2001 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Jan 2001